This invention relates to a sample-sucking condition checking method and system which, incorporated in an apparatus for sucking a liquid-like sample such as a serum, for automatic chemical analysis, judges the sample-sucking condition thereof by monitoring the suction pressure.
Conventionally, an automatic apparatus used, for example, for chemical analysis, is equipped with a device which monitors the sample sucking condition thereof by use of a high-sensitivity pressure sensor. Specifically, this sensor detects any variation in suction pressure upon sucking of the sample. The suction pressure value output from the pressure sensor indicates a given value when a viscosity of the sample to be sucked is within a normal value range and when a proper sucking operation is performed. If the forward end of a sampling nozzle is clogged with, for example fibrin, a suction pressure, greater than a suction pressure within the normal range will be indicated, whereby the clogged condition will then be determined. Where, on the other hand, the sample is not present before the start of the sample suction or during the sample suction pressure will become smaller than suction pressure within the normal range, and thus, the sample sucking condition will be judged as "no sample" condition.
In the conventional device adapted to monitor the suction conditions of the sample, the suction pressure is detected during sample-suction, to thereby obtain a data value which is then analog/digital (A/D)-converted into digital data for recording. After the completion of suction, the suction pressure waveform is analyzed and, in accordance with the suction condition, judged as indicating a "normal", a "clogged", or a "no sample" condition.
Since, however, according to this method, the performing of a proper sample-sucking procedure is delayed, particularly when the "clogged" condition is indicated, the pressure sensor is then subjected to a large pressure, with the risk that it will be damaged, as a result. Thus an conventional system has to judge the suction condition after all the suction pressure values have been collected and recorded.
It is now generally felt desirable that in order that the suction condition, at the time of sample suction, can be judged readily and rapidly, a simpler system should be implemented therefor, that the "clogged" condition be detected earlier, in order to reduce the risk of the pressure sensor being damaged, and that the sample-sucking condition be judged irrespective of, for instance, sample type and sampling tube diameter.